A case of pleomorphic adenoma of the trachea.

An unusual tumor of the trachea was found in a 76-year-old woman. The tumor resembled an adenoid cystic carcinoma in having many cystic spaces, but the fairly uniform tumor cells gradually merged with the myxomatous or hyalinous stroma, and foci of squamous metaplasia and glycogen-rich adenoma-like components were also observed. S-100 protein was demonstrated immunohistochemically in the tumor cells. This tumor was diagnosed as a pleomorphic adenoma (benign mixed tumor) of the trachea.